1. Field of the Invention
This invention relates to an electric extensible car antenna which uses a single small-diameter rod antenna element.
2. Prior Art
In many of the conventional electric extensible car antennas, telescopic extensible antenna elements comprising a plurality of conductive pipes of different diameters movably connected to one another are employed.
With an electric extensible car antenna in which an extensible antenna element of this type is used, there is a large risk that the antenna element and its surrounding areas will become damaged upon impact if an object comes into contact with the antenna element in its extended state while the car is running or being washed. In this case, the degree and location of damage varies depending on the type and size of the object making contact, as well as on the conditions under which the contact occurs.
However, in general, since the portions of the small diameter sections toward the proximal end of the antenna element are quite flexible, the degree of damage is relatively small in these areas. In contrast, the portions of the large diameter sections toward the distal end of the antenna element are not very flexible. Therefore, when an object such as a large washing roller touches it, for example, it may become sharply bent or even broken.
To avoid such a mishap, it is possible to employ an antenna element comprising a single rod having a small diameter, which provides great flexibility throughout the antenna element. However, an antenna element comprising a single rod having a small diameter has the following problems:
When such an antenna is used, the entire antenna element attains great flexibility. Because of this, even if a large force is exerted on the antenna element, the impact is greatly reduced by the resilience of the antenna element. Accordingly, there is a small risk of the antenna element being damaged or broken.
However, because the diameter of the antenna element is small throughout the antenna's entire length, it is naturally necessary to make the antenna element support member of an antenna attachment base small as well, which complicates construction and makes manufacturing difficult. In addition, the antenna element support member tends to invite rattling, which makes it difficult to attach the antenna element to the car body in a stable fashion.
Further, when an antenna element comprising a single rod having a small diameter is used, even when the antenna element is pulled into the car body for storage, the length of the antenna element itself does not become smaller. Therefore, there is a major problem regarding how to store the lengthy antenna element in a small space inside the car body. In addition, because it is difficult to move the long rod antenna element using an electric mechanism, it becomes difficult to create an electric extensible antenna.